W 36X232 vs UB 914×419×343
W 36X232 is an W section from the American AISC Shapes Database; UB 914×419×343 is the closest equivalent in the UK Blue Book (SCI P363). They are close to interchangeable in bending: 15338.3 cm³ against 15500 cm³ of plastic modulus, a difference of 1.0%. They weigh essentially the same, 345.3 kg/m and 343.3 kg/m. W 36X232 is deeper, 942.3 mm against 911.8 mm, which matters where the floor zone is tight.
| Property | W 36X232 W | UB 914×419×343 UB | Difference |
|---|---|---|---|
| Mass | 345.3 kg/m | 343.3 kg/m | +0.6% |
| Depth | 942.3 mm | 911.8 mm | +3.3% |
| Width | 307.3 mm | 418.5 mm | -26.6% |
| Web thickness | 22.1 mm | 19.4 mm | +13.9% |
| Flange thickness | 39.9 mm | 32 mm | +24.7% |
| Area | 438.7 cm² | 437 cm² | +0.4% |
| Second moment, major (Iy) | 624,347 cm⁴ | 626,000 cm⁴ | -0.3% |
| Plastic modulus, major (Wpl,y) | 15,338.3 cm³ | 15,500 cm³ | -1.0% |
| Elastic modulus, major (Wel,y) | 13,257.1 cm³ | 13,700 cm³ | -3.2% |
| Second moment, minor (Iz) | 19,480 cm⁴ | 39,200 cm⁴ | -50.3% |
| Plastic modulus, minor (Wpl,z) | 1,999.2 cm³ | 2,890 cm³ | -30.8% |
| Radius of gyration, minor (iz) | 6.65 cm | 9.46 cm | -29.7% |
| Torsion constant (It) | 1,648 cm⁴ | 1,190 cm⁴ | +38.5% |
W 36X232 to AISC Shapes Database v16.0; UB 914×419×343 to BS EN 10365:2017. Difference is expressed relative to UB 914×419×343.
How to choose between them
On stiffness, UB 914×419×343 has the larger second moment of area: 626,000 cm⁴ against 624,347 cm⁴, a difference of 0.3%. This matters more often than the strength comparison, because on normal floor spans deflection rather than bending capacity sets the beam size - so if the two are close on modulus but apart on inertia, the stiffer one is usually the better answer even when it is not the stronger one.
Measured as bending capacity per kilogram, the two are equally efficient (44.4 against 45.2 cm³ per kg/m), so on a pure steel-tonnage basis there is nothing to choose between them. The decision comes down to availability, connection detailing and what the rest of the frame uses.
The two diverge much more about the minor axis: UB 914×419×343 has 2890 cm³ of minor-axis plastic modulus against 1999.2 cm³, 30.8% more. If the member sees any minor-axis bending, or if it is unrestrained over a long length and lateral-torsional buckling governs, that gap decides the comparison even though the major-axis numbers looked equivalent.
These come from different catalogues, so treat the swap as a design change rather than a like-for-like substitution. W sections are specified to AISC Shapes Database v16.0 and UB to BS EN 10365:2017; the steel grades, tolerances and available lengths differ, connection details and bolt gauges are set out differently, and the two are rarely both stocked in the same market. Check availability before changing a section on a drawing to save a marginal amount of weight.
In short, these two are genuine equivalents. Pick whichever your supplier stocks and the rest of the frame already uses.